Richard Jackson, MD
Ashley M. Wabnitz MD et al. introduced the finding that despite the superiority of aggressive medical management (AMM) in intracranial atherosclerotic arterial stenosis (ICAS), 15% of patients still had primary end point of stroke during a median follow up of 32.4 years.
The study was a post-hoc analysis of 154 patients of the total 227 patients with intracranial stenosis randomized to AMM, 49 ICA and 105 MCA. Non-MCA territory infracts and stenosis were excluded, as well as 53 patients for baseline imaging not corresponding to the qualifying event. All patients included in SAMMPRIS had angiographically verified 70-99% stenosis of ICA, MCA, vertebral or basilar arteries. Infarct patterns were classified into core, perforator, internal borderzone, or cortical borderzone based on published templates from a retrospective analysis of WASID lesions. Interobserve agreement for infarct patterns was k=0.8. Evaluation of collaterals was assessed by a validated scale by the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology; however, collaterals were assessed as impaired versus not impaired despite the validated scale having 4 grades.
52% of the patients had borderzone infarcts as their inclusion criteria, and 48 had angiographically defined impaired flow. 19% of the 101 qualifying patients for this analysis had a recurrent event in the 32.4 month follow. Of these, 26.4% had borderzone infarct patterns, and in this group, 69.8% had impaired flow angiographically. There were 55 patients out of 87 with borderzone infarcts in the stenting arm of SAMMPRIS, and 53 out of 101 patients in the AMM arm. 18.2% of the patients in the stenting arm had a recurrent stroke versus 26.4% in the medical arm p=0.3 HR 0.65.
The investigators conclude that patients with borderzone infarct patterns are high risk for recurrence and were more likely to have impaired collaterals. The same was found in WASID with recurrence and poor collaterals, but no correlation between collaterals and borderzone infarcts however WASID enrolled 50-99% stenosis and different collateral classification grades. The evaluation showed that the endpoint of stroke was lower in the stenting arm vs the aggressive medical management in borderzone infarcts.
The limitations of the study included underpowered comparisons, collateral assessment limited to 82 of the 101 patients, and a single rater for collateral patterns.
